Box sealing machines including upper and lower taping heads for applying lengths of pressure-sensitive adhesive tape to a box or carton driven through the machine are generally well known. Moreover, the provision of means for folding the box flaps so as to close such a box in combination with the taping heads of box sealing machines is also well known. Such means for folding the top box flaps typically include a ski which is supported from an upper cross member assembly so as to engage and fold a leading minor flap of a box, major side flap folding guides or rods which engage the major side flaps as the box moves forwardly so as to urge them downwardly to their closed position, and a trailing minor flap folding assembly which folds the trailing minor flap prior to the closing of the major side flaps. After the folding is completed, an upper taping head seals the top of the box by a length of tape applied to the upper major side flaps. Normally, at the same time a lower taping head applies a length of tape to the lower major side flaps.
The trailing minor flap folding assembly is known to comprise what is hereinafter referred to as a kicker which is pivotally supported from the upper cross member assembly and which is driven by a means, such as a pneumatic cylinder, to engage with and to fold the trailing minor flap before the major side flaps are folded by the major flap folding guides or rods. In order to accomplish this, the kicker must be timed with respect to the position of the box along the machine and the major flap folding guides or rods. Typically, a means which senses the relative position of a box for actuating the kicker drive means is used. Such means may detect either the front edge or the rear edge of the box. Known sensing means include the use of photocells, limit switches, and levers which are actuated by engagement with or disengagement from either the box front edge or rear edge. Furthermore, the kicker must be repositioned in its raised position after the box has passed through at least the folding portion of the machine in preparation for the next box to be driven through the machine. This reposition may occur as a result of the box moving from and deactivating such a limit switch or photocell, or by activating yet another such sensor provided farther downstream. The addition of more sensors disadvanteously increases the complexity of the machine control system; however, the use of the same sensor to control raising and lowering has heretofore been inadequate in that the machine lacks versatility.
In order to control feeding of subsequent boxes into the box sealing machine, it is further known to provide a mechanism for preventing entry of the next box into the box sealing machine until after a first box is sufficiently driven through the box sealing machine and the folding mechanism is reconfigured back to its ready position for receiving the next box. Such a mechanism is known to include devices which block entry of subsequent boxes into the box sealing machine that engage with the next box and which permits passage at an appropriate time. One known device comprises a gate pivotally mounted to the machine bed which is movable between a blocking position above the plane of the bed and an open position below the plane of the bed. Such gates can be conventionally movable between the blocking and open positions by a pneumatic cylinder, and can be controlled in a similar manner as the kicker assembly, discussed above, by the provision of sensors, such as photocells, limit switches, or levers, to permit passage of the next box into the machine only after the previous box passes a certain point along the machine. Moreover, in order to initiate both the blocking and open gate positions, either a plurality of sensors are required, one for defining each position, or the gate positions must be determined by the actuation or not of a single sensor. Since it is important that the gating device be timed with respect to the other operations of the box sealing machine, including any kicker mechanism or other flap folding device, it is difficult to control the necessary machine configurations without a multiplicity of sensors for each such operational mechanism while permitting versatility to adjust the machine to provide optimum setting for a particular box. The use of so many sensors greatly increase the complexity of the control system, such as a pneumatic circuit, for such a box sealing machine. In particular, each sensor is typically associated with a valve of a pneumatic circuit thus rendering the pneumatic circuit more complex and costly. Any compromise as to the number of sensors needed results in a less efficient and less versatile machine due to problems in coordinating the related activities of the machine or by slowing down the number of boxes which can pass through the machine for a given time period.
Another problem common to prior art box sealing machines involves the provision of the upper taping head and any upper box flap folding mechanisms, such as a ski and/or kicker, supported from an upper cross member. Typically, such an upper cross member is vertically adjustably supported from the machine base so as to position the upper taping head and any box flap folding mechanisms at the appropriate level for a specific box driven through the machine. Such adjustment may be automatic or manual. The problem is that it is difficult to ensure that the upper taping head and/or the box flap folding mechanism are properly level to adequately perform their related functions. Moreover, such problem is worsened over time and usage of the machine. The taping head and box folding mechanism are typically rigidly cantilever mounted to the upper cross member. Thus, it is imperative that at original construction, the upper taping head and box flap folding mechanism be accurately aligned and connected to the upper cross member. Moreover, the pressures exerted on such connection during usage of the machine over time may tend to cause slight deformation at the connection, thereby unleveling the upper taping head, the box flap folding mechanism, or both.
Examples of box sealing machines including upper taping heads supported by an upper cross member are described in: U.S. Pat. No. 4,633,642 to Lissoni, U.S. Pat. No. 4,238,269 to Deering, Jr., U.S. Pat. No. 4,028,865 to Loveland et al, and U.S. Pat. Nos. 4,748,794, 4,653,247, 4,643,707, 4,585,504, and 4,541,888 and the British Patent Specification No. 1,585,335 to Marchetti.